2709 Sagan

2709 Sagan, provisional designation 1982 FH, is a stony Florian asteroid from the inner regions of the asteroid belt, approximately 6.7 kilometers in diameter. It was discovered on 21 March 1982, by American astronomer Edward Bowell at Lowell's Anderson Mesa Station near Flagstaff, Arizona, and named after astronomer and science popularizer Carl Sagan.[2][8]

2709 Sagan
Lightcurve-based 3D-model of Sagan
Discovery [1]
Discovered byE. Bowell
Discovery siteAnderson Mesa Stn.
Discovery date21 March 1982
Designations
(2709) Sagan
Named after
Carl Sagan (astronomer and science communicator) [2]
1982 FH · 1951 WF1
1959 CC · 1959 EA1
1964 WT · 1982 FE2
main-belt · Flora [3]
Orbital characteristics [1]
Epoch 4 September 2017 (JD 2458000.5)
Uncertainty parameter 0
Observation arc58.15 yr (21,239 days)
Aphelion2.3475 AU
Perihelion2.0428 AU
2.1952 AU
Eccentricity0.0694
3.25 yr (1,188 days)
319.11°
0° 18m 10.8s / day
Inclination2.7318°
241.13°
308.48°
Physical characteristics
Dimensions6.559±0.196 km[4]
6.81 km (calculated)[3]
5.254±0.001 h[5]
5.2557±0.0002 h[lower-alpha 1]
5.2564±0.0007 h[lower-alpha 2]
5.258±0.002 h[6]
0.24 (assumed)[3]
0.259±0.043[4]
SMASS = S [1] · S [3]
12.13±1.03[7] · 13.0[1][3][4]

    Orbit and classification

    Sagan is a member of the Flora family, one of the largest families of stony asteroids. It orbits the Sun in the inner main-belt at a distance of 2.0–2.3 AU once every 3 years and 3 months (1,188 days). Its orbit has an eccentricity of 0.07 and an inclination of 3° with respect to the ecliptic.[1]

    Physical characteristics

    In the SMASS classification, Sagan is classified as a S-type asteroid.[1] It has an albedo of 0.26, according to observations made by the Wide-field Infrared Survey Explorer and subsequent NEOWISE mission.[4] The body has a rotation period between 5.254 and 5.258 hours and a brightness variation between 0.09 and 0.63 magnitude (U=3/3/3/3).[5][6][lower-alpha 1][lower-alpha 2]

    Naming

    This minor planet was named in honor of Carl Sagan (1934–1996), planetary scientist at Cornell University, science popularizer, editor of the journal Icarus, and founder of The Planetary Society. Sagan participated on a number of planetary space missions, including the Voyager mission to the outer planets and the Mariner 9 and Viking program to Mars.

    Sagan's research encompassed studies of the greenhouse effect on Venus, the atmosphere and surface of Titan, windblown dust on Mars, and the possibility of extraterrestrial intelligent life. Sagan won the Pulitzer Prize for literature in 1978.[2] The official naming citation was published by the Minor Planet Center on 4 August 1982 (M.P.C. 7158).[9]

    An asteroid discovered in 1998, 4970 Druyan, is named after Sagan's wife Ann Druyan and is said to be in a "wedding ring orbit" with respect to 2709 Sagan.[10]

    Notes
    1. Pravec, Petr (2016): lightcurve plot of (2709) Sagan with a rotation period of 5.2557±0.0002 hours with a brightness amplitude of 0.63 mag (U=3). Summary figures for (2709) Sagan at Collaborative Asteroid Lightcurve Link (CALL)
    2. Pravec, Petr (2011): lightcurve plot of (2709) Sagan rotation period of 5.2564±0.0007 hours with a brightness amplitude of 0.09 mag (U=3). Summary figures at Collaborative Asteroid Lightcurve Link (CALL)

    References
    1. "JPL Small-Body Database Browser: 2709 Sagan (1982 FH)" (2017-03-29 last obs.). Jet Propulsion Laboratory. Retrieved 14 June 2017.
    2. Schmadel, Lutz D. (2007). "(2709) Sagan". Dictionary of Minor Planet Names – (2709) Sagan. Springer Berlin Heidelberg. pp. 221–222. doi:10.1007/978-3-540-29925-7_2710. ISBN 978-3-540-00238-3.
    3. "LCDB Data for (2709) Sagan". Asteroid Lightcurve Database (LCDB). Retrieved 6 December 2016.
    4. Masiero, Joseph R.; Mainzer, Amy K.; Grav, Tommy; Bauer, James M.; Cutri, Roc M.; Nugent, Carrie; Cabrera, Mario S. (November 2012). "Preliminary Analysis of WISE/NEOWISE 3-Band Cryogenic and Post-cryogenic Observations of Main Belt Asteroids". The Astrophysical Journal Letters. 759 (1): 5. arXiv:1209.5794. Bibcode:2012ApJ...759L...8M. doi:10.1088/2041-8205/759/1/L8. Retrieved 6 December 2016.
    5. Oey, Julian; Inasaridze, Raguli Ya.; Kvaratskhelia, Otar I.; Ayvazian, Vova; Chirony, Vasilij G.; Krugly, Yurij N.; et al. (July 2013). "Lightcurve Analysis is Search of Binary Asteroids". The Minor Planet Bulletin. 40 (3): 169–172. Bibcode:2013MPBu...40..169O. ISSN 1052-8091. Retrieved 6 December 2016.
    6. Higgins, David J.; Pravec, Petr; Kušnirák, Peter; Hornoch, Kamil; Brinsfield, James W.; Allen, Bill; Warner, Brian D. (September 2008). "Asteroid Lightcurve Analysis at Hunters Hill Observatory and Collaborating Stations: November 2007 – March 2008". The Minor Planet Bulletin. 35 (3): 123–126. Bibcode:2008MPBu...35..123H. ISSN 1052-8091. Retrieved 6 December 2016.
    7. Vereš, Peter; Jedicke, Robert; Fitzsimmons, Alan; Denneau, Larry; Granvik, Mikael; Bolin, Bryce; et al. (November 2015). "Absolute magnitudes and slope parameters for 250,000 asteroids observed by Pan-STARRS PS1 - Preliminary results". Icarus. 261: 34–47. arXiv:1506.00762. Bibcode:2015Icar..261...34V. doi:10.1016/j.icarus.2015.08.007. Retrieved 6 December 2016.
    8. "2709 Sagan (1982 FH)". Minor Planet Center. Retrieved 6 December 2016.
    9. "MPC/MPO/MPS Archive". Minor Planet Center. Retrieved 6 December 2016.
    10. Palmer, Rob (June 2020). "Exploring 'Possible Worlds' With Ann Druyan". Skepticalinquirer.org. Center for Inquiry. Archived from the original on 1 April 2020. Retrieved 17 April 2020. [...] asteroids named after each of us that are in perpetual wedding ring orbit around the Sun. Imagine one orbit. And then imagine that the orbit of the other asteroid goes in and out of the other's orbit. So, if you had two wedding rings that were linked together, that's a wedding ring orbit.

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